1. Field of the Invention
The present invention relates to a combustion engine for use mainly in an automotive vehicle such as, for example, a motorcycle and, more particularly, to an arrangement of an oil cooler and an oil filter disposed on an oil supply passage for the supply of an engine lubricating oil to the combustion engine and also to a lubricating device for supplying a lubricating oil to the combustion engine and a transmission.
2. Description of the Prior Art
In the four cycle combustion engine used in motorcycles now in use, the oil filter and the oil cooler are generally mounted on a crankcase, having been spaced a distance from each other and, therefore, a piping system including engine oil passages within the crankcase tends to become so complicated as to result in reduction in productivity and increase of the cost. The Japanese Laid-open Patent Publication No. 2005-48725, published Feb. 24, 2005, discloses a unitary structure of the oil filter and the oil cooler, which is installed in a lower portion of a front surface of the crankcase.
Considering that in the motorcycle combustion engine, a cylinder block of the combustion engine is generally mounted atop the crankcase and a motorcycle transmission is arranged at a rear portion thereof, the motorcycle combustion engine has a center of gravity located in the vicinity of a root portion of a rear surface of the cylinder block. However, since in the previously mentioned patent document, the unitary structure of the oil filter and the oil cooler, that is, a combination filter and cooler unit is arranged at a lower portion of the front surface of the crankcase, the mass of the combustion engine is dispersed and, therefore, the mass distribution of the combustion engine tends to be unfavorable from the point of a weight balance. Also, the positioning of the combination filter and cooler unit at the lower portion of the front surface of the crankcase tends to impose limitation in the layout of the motorcycle exhaust pipe.